We describe a two-pronged approach aimed to increase the supply of islets available for transplantation. First, techniques for in-vitro islet expansion based upon fibrin-matrix and HGF stimulation have been developed. These techniques could increase the islet mass isolated from single donors. The first aim is to quantitate and characterize the quality of in vitro HGF/fibrin-expanded human islets, and then assess in-vivo unction using a diabetic mouse model of human islet transplantation. Second, cryopreservation methods based on trehalose have been developed and could be used to store both expanded islets as well as fresh islets from marginal mass isolations. Such cryopreserved islets can later supplement a standard islet transplant to yield a total islet mass large enough to achieve insulin independence in a single infusion. The second aim is to assess the quality of cryopreserved fresh and ixpanded islets after thawing, and then assesses in-vivo function a diabetic mouse model of human transplantation. Both aims represent the next experimental step in a logical progression towards translation if these techniques into clinical trials of human islet transplantation.